Safety brake control mechanism



Dec. s, 1942. R, E. COX 2,304,546

SAFETY BRAKE CONTROL MECHANISM ATTORNEY Dec. s, 19424.

R. E. COX

SAFETY BRAKE CONTROL MECHANISM 3 Sheets-Sheet 2 Filled Jan. 2l, 1941INVENTOR ,Pm/mond ./5 6 X my 65;

AILTORNEY Dec. s, 1942.

R. E. cox SAFETY BRAKE CONTROL MECHANISM Filed Jan. 2l, 1941 3Sheets-Sheet 3 INVENTOR /Pamomc/f Qox BY ,3% A; ATTORNEY Patented Dec.8, 1942 UNITED STATES teint iiATENT OFFICE 7 Claims.

The invention relates to safety brake control mechanisms for automotivevehicles and trailers and the like of the type generaly disclosed by myprevious Patents Nos. 2,128,916 and 2,188,200.

In the control system to which the present invention relates, the brakesof the automotivevehicle are automatically applied in the event theoperator of the Vehicle starts to fall asleep or otherwise momentarilylapses and releases his grip of the steering wheel, whereby the vehiclewill be promptly brought to a safe stop. The mechanism utilized in thesafety control consists of electrically and mechanically operateddevices embodied in the pneumatic or iluid circuit of the brake assemblyfor the vehicle and which is in turn electrically operated by switchmeans care ried by the steering wheel of the Vehicle, the switch meansbeing so arranged on the steering wheel that the same is automaticallyoperated upon gripping and releasing of the wheel. In previous systemsthe setting into operation 'of the pneumatic brake mechanism wasdependent upon a closing of the electric circuit by the aforementionedswitch means. rIhis feature of the system has the disadvantage that anopening of the electric circuit at any part thereof due to wear oraccident, will prevent the automatic operation of the system. Inaccordance with the present invention and as a principal object thereof,the present system is arranged to operate upon the opening of theelectric control circuit whereby positiveness of operation upon releaseof grip of the steering wheel will be insured. y

Another important object of the present invention is to provide a systemof the character described which will automatically apply the brakes ofthe vehicle in the event of a predetermined and inherent dangerousdepletion of the fluid pressure source.

A further object of the invention is to pro- Vide a brake control systemof the character above which may be readily applied to existing types ofautomotive Vehicles and is especially designed for adaptability to truckand trailer yvehicles and is operative in the latter instance toautomatically simultaneously apply the brakes of both units with aretarded action in the propelling with the usual manual foot controlbrake valvesv and while will be automatically rendered inoperaof theautomotive vehicle.

tive to produce an emergency stop of the vehicle when the operator iscontrolling the vehicle through the use of the manual or foot controlbrake Valves.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of the preferred form of the invention which is illustratedin the drawings accompanying and forming part of the specification. Itis to be understood, however, that variations in the showing made by thesaid drawings and description may be adopted within the scope of theinvention as set forth in the claims.

Referring to said drawings:

Figure 1 is a diagrammatic representation of a brake control systemconstructed in accordance with the present invention, the severaloperating members of the system being illustrated in cross section.

Figure 2 is a view similar to Figure l but show-` ing the systemmodified for use with a vacuum power source.

Figure 3 is a front elevation of a steering wheel constructed inaccordance with the present invention, a portion of the wheel beingbroken away and illustrated in section.

Figure 4 is a cross sectional View of the steering wheel illustrated inFigure 3 and is taken l f substantially on the plane of line 4 4 ofFigure 3.

The safety brake control system of the present invention is illustratedin Figure 1 in conjunc tion with an air pressure brake system andincludes as part thereof a reservoir 5 which is charged with compressedair or other fluid by way of an inlet conduit 'l and check valve 8therein for maintaining the pressure in the reservoir. The reservoir isconnected to a multiple outlet fitting 9 and thence by a conduit ill toa foot .10 Control valve Il. The latter is normally opened and closedand regulated as to quantity of air how by displacement ci an operatinglever l2 which is connected by link i3 to a foot pedal I4 normallypositioned in the drivers compartment The air under pressure passes fromvalve I l by way of conduit lr6 to a two-way check valve l1 and thenceby way of conduit I3 to the air brake chambers of the brake mechanism ofthe vehicle. These air brake lchambers are well known in the art andtherefore are not here shown. The foot control valve H is of more orless standard construction and fully disclosed in my prior patentsaforementioned, and consistsbriefly of a casing having inlet anddischarge passages i9 and 2| to which the conduits l and i6 areconnected. Passage openinto a valve chamber E adjacent tho top thereof,which chamber opens to an enlarged pressure chamber 23, A reciprocalvalve 2d r" mounted in the chamber 22 and is normally elel vated to aseated position by means of a helica spring 25 mounted thereunder. Thevalve is provided with a stem 21 which extends into the chamber 2S andinto engagement with the underside of a swivel plate 28 whi-ch isfulcrumed adjacent the center thereof to the under-side of a pressureresponsive diaphragm 2Q mounted across the chamber 23. Means isprovi-ded for venting chamber 2S and the discharge conduit 1G to theatmosphere upon closing of valve 2li and in the present constructionthis means consists oi a second valve chamber Si communicated with thechamber 2S and to the atmosphere by way of a port 32. A reciprocal valve33 is mounted in chamber 23 in position to engage and close ofi the topof chamber 3i and is normally held in unseated position by means of ahelical spring mount-ed in the valve chamber 3i. rl`jhe valve 33 isprovided with an upwardly enten-:ling stem which engages the under-sideof the swivel plate 28 on the opposite side of its iulcrum from thcvalve stem 21. Spring Sli is constructed somewhat lighter than spring 2Gso that upon depression of the swivel plate 28, the latter will rock toclose valve 33 before opening of valve The swivel plate 2.. is depressedby operation of the control lever E2 which, as will be seen, is pivotedto the casing and is engageable with the upper end of a stem S8 of aspring rest bearing against the upper end of a helical spring 31supported on the diaphragm 29 by a supporting member 38 which extendsthrough the diaphragm to provide the fulcrum point of plate 2S. From theforegoing it will be clear that upon depression of the foot table I4,air under pressure will pass from conduit lil into chamber '23 throughopen valve 2G and thence out through the discharge passage 2i andccnduit Upon release of the foot table, valve 2t moves to a seatedposition to seal ofi the incominor compressed air and valve 33 opens soas to vent the chamber and the discharge conduit i3 to the atmosphere.

As above indicated, the present system ig arranged for application ofthe brake units of a trailer and as will be seen from Figure l, thetrailer brakes are normally manually operated by means of a hand valve39 which is preferably mounted in th-e drivers compartment of thepropelling vehicle and which receives compressed air by way of conduit iand is connected by a discharge conduit 42 to a two-way check valve 43and thence by conduit llito the air brak-:- Cham bers of the trailer.The valve 33 is here shown of a rotary type including an outer valvecasing 46 and an interior rotor 1 having a pair or" circumferentiallyspaced side ports 8 and 19. In the normal olif-position of the valve, asillustrated in Figure l, the port 45 communicates a discharge passage5i, to which the conduit d2 is connected, to an atmospheric passage Uponrotation of the rotor in a clock-wise direction, as by means of handle53, port 'i3 moves into registration with an inlet passage Sil, to whichconduit 4i is connected and discharge passage 5i, so as to passcompressed air from reservoir 6 to the trailer brake chambers.

In accordance with the foregoing, it will be clear that the operator ofthe propelling vehicle may by manual actuation of the foot pedal I4 andthehandle 53 bring the propelling vehicle and thev trailer vehicle to astop. Ordinarily in so using the manual controls, the operator will rstdisplace the handle 53 to set the brakes of the trailer unit prior todisplacing the foot table i4 to set the brakes of the propelling unitand will in the operation of these two controls maintain a slightlygreater braking force on the trailer than on the propelling unit so asto bring both units to a smooth safe stop without jack-limiting of theunits.

The automatic control of the present invention is so designed andconstructed and connected in the aforementioned fluid circuits so as toprovide an automatic setting of both the trailer and the propellingvehicle brakes upon release of the steering wheel of the vehicle. Aswill be seen from Figure 1, compressed air for the automatic circuit iswithdrawn from the multiple fitting 9 by way of a conduit 56 to areducer valve 51 and thence by conduit 58 to a pneumatically operatedvalve mechanism 59 and thence by conduit 6I to the truck and trailerbrake units. In order to provide a delayed operation of the brake unitsof the propelling vehicle, an air flow retarder 62 is connected betweenthe conduit 6| and the twoway check valve l1 to which the propellingvehicle brake chambers are connected.

The valve mechanism 59 here consists of a valve body 63 havingopposed-ended valve chambers G4 and 66 opening into an interior 51provided with a discharge passage 68 to which the conduit 6I isconnected. Mounted n the lower chamber 66 for reciprocation to and froma valve seaty 69 in the top of the chamber, is a valve 1l which isnormally urged to closed position by a helical spring 12 compressedthereunder and which is provided with a valve stem 13 which extendsupwardly through the chamber 61 and into the chamber 64. A Valve 14 ismounted in the upper chamber 64 upon the stem 13 so as to move in unisonwith the valve 1l and is normally urged to seated position by a helicalspring 1:3 compressed between the top of the valve 14 and the upper endof the valve chamber 64. In accordance with the present construction,the spring 16 is of somewhat heavier construction than the spring 12 andexerts a greater force whereby the valves 14 and 1l are normally urgedto a seated and unseated position respectively. The lower valve chamber66 is provided with an inlet passage 11 to which the conduit 58 isconnected so that in the open position of the valve 1|, air underpressure is permitted passage from the inlet passage 11 through theinterior chamber S1 and out through the discharge passage 68, to operatethe brakes. 0n the other hand in the seated position of valve 1I andcorrespondingly open position of valve 14, the interior chamber 61 iscommunicated with valve chamber 64 which is in turn vented to theatmosphere by way of a side port 18. In this position of the valvestructure, compressed air in conduit El may return through chamber 61and be discharged to the atmosphere through port 18.

Displacement of Valves 'Il and 14 is here arranged to be effected bymeans of a pneumatic actuator associated with the valve structure. Aswill be seen from Figure l, the valve body'63 is mounted on the top of acasing 19 which is formed with an interior air chamber 8l divided intoupper and lower vertical compartments by a flexible diaphragm S2.Compressed air may beV entered into thelower compartment of the chamberunder the diaphragm by way of an inlet passage 83 to which a conduit-84is connected. Mounted on the upper side of the diaphragm in the chamberis a plate 86 which supports a plurality of vertically extendingpush-rods 81 and` 88 which extend through the top wall of the casing 19and are Lconnected at their upper ends by a cross member 89. Anextension 9| of the valvestem 13 is secured to the cross member 89whereby upon application of pressure in the lower chambercompartment andelevation of the plate 86, the valve'members 1| and 14 will be elevatedto seat valve 1| and unseat valve 14. On the other hand upon release ofpressure in the lower compartment of the valve chamber, the upper spring16 will cause a downward movement of the valves to seat valve 14 andunseat valve 1|. A lock-nut 92 is preferably provided upon the stemextension 9| and which is engageable with the top Wall 93 of the valvebody to hold the valve in a raised position when desired against theoperation of the upper spring 16.

Air pressure for controlling the operation of the pneumatic actuator asaforementioned is supplied through a solenoid or magnet valve mechanism94 which is in turn electricallyfcontrolled from the steering wheel ofthe vehicle, as will be presently described. The valve mechanism 94consists of a valve body 96 providing opposedended valve chambers 91 and98 formed at the opposite sides of an interior chamber 99 communicatedwith each of the valve chambers. The lower valve chamber 38 is formedwith a valve seat at the upper side thereof which is opened and closedby a Valve normally elevated to a seated position by a helical spring|02 pressed between the under-side of the valve and the lower end of thevalve body. Theupper chamber 91 is provided with a valve seat at thelower end thereof which is opened and closed by a Valve |03 which isconnected to valve |0| for jointy movement of the valve by a commonvalve stem |04. Air under pressure is entered into the lower valvechamber 98 by way of conduit |06 connected to conduit 59 and to an inletpassage |01 in the valve body. The intermediate chamber 99 is connectedto the conduit 84 leading to the penumatic actuator and the upper valvechamber 91 is vented to the atmosphere by Way of a discharge port |08. Asolenoid actuator is mounted at the upper end of the valve body andincludes a magnet coil |00 and a central plunger which is connected toan upper extension of the valve stem |04. In the de-energized positionof the coil |09, the valves I0| and |03 are elevated to a seated andunseated position respectively and in an energized position of the coil,these valves are moved downwardly to seat valve |03 and to unseat valve|0|. Thus in the energized position of the solenoid valve mechanism, airunder pressure passes through the solenoid valve to the pneumaticactuator to prevent the passage of compressed air to the brake units. Onole-energizing the solenoid valve mechanism, air is discharged from thepneumatic actuator by way of conduit 84 and valve |03 to the atmosphereand valve 8| is opened to pass compressed air to the brake units.

As mentioned in the foregoing, control of the system and moreparticularly control of the solenoid actuator is here effected from thesteering wheel ||2y of the vehicle. The latter is so constructed toembody an electric switch means ||3 in a manner providing for theoperation of the switch means upon gripping an'd releasing of thesteering wheel. In accordance with the present construction and as moreclearly illustrated in Figure 4 kof the drawings, the switch meansassumes anopen position upon release of the steering wheel and is movedto a closed position upon gripping of the steering Wheel. The switchmeans is connected in an electric circuit including the magnet coil |09and a source of electrical potential such as a battery ||4. As will beseen from Figure 1, one side of the battery is grounded to the chassisof the vehicle by means of a conductor IIB and the opposite side of thebattery is connected to a current limiting fuse ||1 and thencey byconductor ||8 to the coil |09 and thence by conductor I9 to one side ofthe switch means ||3, the other side of the switch means being grounded.It will thus be seen that upon gripping of the steering wheel andenergizing of the solenoid actuator 93, air pressure will pass from thereservoir 6 through the solenoid actuator valve |0| to the pneumaticactuator to close valve 1| and prevent passage of compressed air to thebrakes. Upon release of grip of the steering wheel and opening of theelectric circuit, the application of pressure to the pneumatic actuatoris interrupted and valve 1| is open to cause passage of compressed airto the brake units.

In order that the operator of the Vehicle may prevent an undesiredautomatic operation of the braking system during moments when it isnecessary to remove his hands from the steering wheel, I prefer toinclude a foot switch |2| in the electric circuit in parallel with theswitch means I3 whereby the operator of the Vehicle may engage anddisplace the foot switch to maintain the electric circuit closed whennecessary to release his grip of the steering'wheel. The switch |2| ishere of a simple push type including spaced electric contact members |22and |23 which are engaged and disengaged by a bridge contact |24normally held out of engagement by a spring |26. The bridge contact |24is carried by a pusher member |21 which may be engaged and depressed bythe foot against the resistance of spring |26 in order to close theelectric circuit through the switch. As here shown contact member |22 isconnected by conductor |23 to conductor ||9 while contact member |23 isgrounded.

'I'he reducer valve 51 is preferably used in the automatic control inorder to prevent the sudden application of the full reservoir pressureto the brake units. In the case of the manually controlled valves, theoperator can regulate the amount of pressure applied to the brakes andaccordingly a reducer in the line is not necessary. The reducer valvecomprises a valve casing t28 having an inlet passage |29 to whichconduit 59 is connected and the discharge passage I3! to which conduit58 is connected. Inlet passage |29 opens to a valve chamber |32 which isprovided at an opposite end with a valve seat |33 which surrounds apassage opening into a chamber |38 to Which the discharge passage l3| isconnected. Mounted in the chamber |32 for movement to and from the seat|33 is a valve |36 having a stem |31 passing through the seat openingand secured to a diaphragm |38 mounted across the base of chamber |34.The valve is normally held in partially open position by means of aspring |39 compressed between a supporting plate at the diaphragm and aspring seat |4| at the inner end of a screw |42 threaded through thecasing at the top of chamber |34. In accordance with this constructionvalve |36 will move in accordance with fluctuations in the pressure atthe intake passage |29 to produce a substantially constantand reducedoutput pressure. The reduced output pressure may be controlled byadjustment of the screw |42.

The two-way check valves I1 and 45 permit the coupling of the manualcontrols and the automatic control to the truck and trailer brake units.These check valves are in each instance composed of elongated cylinders|43 having passages |44 and |46 opening to the opposite ends thereof anda passage |41 opening to the center of the length of the cylinder. Adouble ended piston valve |48 is mounted in the cylinder for end-wisereciprocation therein so as to cover and uncover the passages |44 and|46. In the case of check valve l1, conduit |6 leading from the footcontrolled valve is connected to passage |46 and the opposite endpassage |44 is connected by conduit |49 to the flow retarder 62connected to the automatic control circuit. Conduit i8 leading to thetruck brake units is connected to the central passage |41. In thismanner when the brakes are operated by the foot control valve,compressed air enters passage |46, pushes piston |48 to the opposite endof the cylinder and passes out of passage |41 to the truck brake units.ln

the automatic operation, compressed air enters i.

the cylinder through passage |44, pushes piston |48 to the opposite endof the cylinder and discharges to the truck brakes through the centeropening |41. In a similar manner in the case of the double check valve43, conduits 42 and 6| g are connected to the opposite ends of thecylinder and conduit 44 leading to the trailer brake units is connectedto the center passage of the cylinder.

The flow retarder 62 here used as aforementioned to cause a fastersetting of the trailer brakes than the truck brakes here comprises acasing |53 providing an interior cylinder in which is mounted areciprocating piston valve i5 adapted for movement between the oppositeends .5;

|56 and |51 of the casing. The piston valve |54 is provided with areduced axial bore |58 therethrough which is somewhat smaller than thepassage provided by the other conduit of the system so as to restrictthe fluid ow from conduit 6| to the truck brake conduit I6. The deviceis, however, constructed to provide a rapid and unrestricted luid flowin a reverse direction. This is eiected by providing the valve |54 witha plurality of longitudinal grooves |59 in the periphery thereof, whichconnect with radial grooves |6| at one end of the valve which engagesthe end |56 of the casing. In this manner when the fluid ow is from leftto right as viewed in Figure 1, the piston is displaced to end |51 ofthe casing and the fluid passage confined to the axial passage |56. Onthe other hand when the fluid flow is in a reverse direction, the pistonis pressed against end |56 of the casing and in this case the fluid maypass not only through the axial bore |58 but also through thelongitudinal grooves |59 and the radial grooves |6l.

It is desirable that the automatic control system be renderedinoperative during any period of manual operation of the foot brake ofthe vehicle so that the operator when using the foot brake will havefull and exclusive control of the braking system. This feature isprovided in the present system by the provision of an electric switch|62 which is operatively connected for e actuation to the foot pedal |fland the foot brake valve and is electrically connected across the switchmeans ||3 at the steering wheel whereby upon advancing the brake pedali4 the switch means |62 will be closed to retain the electric controlcircuit closed. As illustrated in the drawings, the switch means |62includes a pair of electric contacts |63 and |64 which are connected byconductor |66 to conductor H9 of the electric control circuit and byconductor |61 to ground. A bridge contact member |68 is mounted on aguided stem member |69 for movement to and from engagement with contacts|63 and |64 and is normally urged out of such engagement by a spring|1|. Stem |69 is connected by means of a threaded adjustment member |12and a spring |13 to the operating lever I2 of the foot valve so thatupon displacement of the valve, the switch will be moved to closedposition and upon return movement of the valve the switch willautomatically move to open position.

The steering wheel and electric switch combination used in the presentsystem is best illustrated in Figures 3 and 4 of the drawings. As willbe seen from Figure 4, the steering wheel ||2 is provided around itsentire periphery on the underside of the wheel with an annular recess|14 defined between substantially rightangularly related walls |16 and|11. At the intersection of these walls at the base of the recess isformed an annular groove |18 within which is mounted a continuousannular coil spring Imember |19. An annular contact ring |9| is embeddedin wall |16 of the recess and a plurality of contact strips |82 aresecured to the coil spring |19 at circumferentially spaced positionsthereof and extend inwardly into opposed position relative to thecontact ring |8| and may be displaced inwardly to engage the ringagainst the resilient resistance of the spring |19. An annular covermember |83 is provided for the recess |14 which is 4preferably made fromflexible material such as rubber or the like and which is vulcanized,cemented or otherwise secured along one side thereof to side wall |11 ofthe recess. The opposite end portion |84 of the cover member |83 ispreferably formed of a relatively soft material such as sponge rubberand engages wall |16 of the recess outwardly of the contact ring 8|. Aswill be seen from Figure 4, the cover member I 83 lies on the outside ofthe contact strips |82 whereby upon gripping of the wheel by theoperator, the cover member |83 may be compressed inwardly to close theelectric contact members. Since all of the contact strips |82 areelectrically connected to the spring |19 and since the ring |8| providesa continuous annular contact member, a movement of any of the contactstrips into engagement with the ring |8| will close the electriccircuit. Preferably, a metal reenforcing ring |86 is provided in thebody of the steering wheel |I2 and is joined with a plurality of metalreenforcing members |81 extending through the spokes of the steeringwheel to the central hub thereof. Since the core members |86 and |81 arenormally electrically grounded to the chassis of the vehicle, I preferto electrically connect the coil |19 to the core ring |86 to facilitateelectrical connection of the switch contact members. This is hereeffected by a short electrical connector |88 extending between thespring |19 and the core |86. An electrical connector |89 is extendedthrough one oi' the spokes of the steering wheel to engage the contactring |8|.

It will be clearly understood from the foregoing that upon gripping ofthe steering wheel and closure of the electric control circuit, theautomatic brake control means is held in check to be placed in operationupon opening of the electric control circuit. Normally of course thecontrol circuit is opened and closed only by v`,operation of thesteeringwheel switch means ||2 or the foot switch |-2| or the switch means |62associ- -ated with the foot control brake pedal. However, an opening ofthe electric control circuit at any point due to wear, corrosion orfaulty electric connection or the like will cause the brakes to be set,thus positively insuring proper maintenance of the electric controlcircuit and proper operation thereof when required for emergency stopsor other stops made by the operator by the switch control means H3.

Another important feature of the present control system and as mentionedin the objects oi v the invention, is the automatic setting of thebrakes upon partial depletion of the air pressure in the reservoir 6. Aswill be appreciated, one of the most hazardous and dangerous features ofa pneumatic brake system is the possibility of air leakage in the systemor partial or complete failure of the compressor to adequately supplycompressed air to the reservoir. In the present construction a drop ofreservoir -pressure will cause an immediate response at thepneumatically operated valve mechanism 59 to cause a setting of thebrakes. As will be noted from the drawings, the reservoir pressure asreduced by reducer valve 51 is applied to diaphragm 82 to normally closevalve which controls the llow of air to the brakes. Upon reduction ofthis air pressure, the diaphragm will be forced downwardly by spring 'I6to open valve 1| and thereby permit passage of compressed air fromconduit |58 through valve 'll to conduit 6| and to the brake lines. Thisautomatic operation is hastened due to the fact that upon partiallyopening valve 1|, and prior to closing of the upper valve 14, compressedair may discharge to the atmosphere through port 18 until the pressurehas been reduced sufliciently to cause a seating of valve I4 and a fullopening of valve 1|. Due to the bleeding action thus provided, thepressure change for operating the control mechanism will be hastened.

Means is also preferably provided for taking the automatic controlsystem out of operation ewhen the vehicle is out of operation, such aswhen garaged and the like. For temporary stops it is in most instancesdesirable that the brakes of the vehicle be set as soon as the operatorreleases the steering wheel and remains set while the oprator is awayfrom his compartment. Where, however, it is desired to prevent operationof the brakes of the control system during absence of the driver fromthe vehicle, I provide means on the magnet valve for mechanicallyholding the latter in an energized position. This means, as illustratedin Figure 1 of the drawings, consists of a set-screw |9| which isthreaded through a cap |92r at the top of the magnet valve casing toengage and depress a bearing block |93 on the upper end of the plungerBy this means, the operator may by screwing downthe set-screw |9|,mechanically open and hold open magnet valve |0| to maintain an airpressure in the pneumatic actuator for valve overs are made and forother reasons which may occur, such as repair of parts of the system,etc., nut 92 of the valve mechanism 59 may be used to eiiect a similarpurpose.

vhandle for displacing the member.

A modified form of the invention has been illustrated in Figure 2 of thedrawings, wherein the control system is shown operatively applied to avacuum or sub-atmospheric pressure brake system. In this form of theinvention a subatmospheric source |96 is connected by conduit |91 to amultiple outlet fitting |98 and thence by conduit |99 to afoot-controlled va1ve'20l, thence by conduit 202 to a master valve 203and thence by conduit 204 to the truck or propelling Vehicle brakes.Valve 20| is here composed of a simple rotary two-way type having ports206 and 201 in the rotor 208 thereof which are spaced on the peripheryof the rotor to move into and out of engagement with ports connected toconduits |99 and 20| and a port 209 which is open to the atmosphere. Inthe inoperative position illustrated conduit 202 is vented to theatmosphere and conduit |99 is sealed by the rotor. A brake pedal 2|| isconnected to the rotor and when depressed to rotate the rotor in acounter clockwise direction advances port 206 to simultaneously registerwith conduits |09 and 2'02. A spring 2|2- connected to the foot lever2|| normally holdsthe latter in the inoperative position shown. Thetrailer brake units are operated manually by hand valve 2|3 which issimilar in construction to the hand valve 39 illustrated in connectionwith the rst described embodiment of the invention and which is hereconnected to the reservoir |96 by conduit 2|4 and is connected byconduit 2|6 to a master ,valve 2|1, the fluid circuit being thencecompleted to the trailer brakes by conduit 2 |8. The automatic operationis in this instance ralso controlled by a solenoid valve mechanism 94which is connected to the sub-atmospheric source |96 by conduit 2|9 andis connected by conduity22| to two pneumatic actuators 222 and 223 forthe master valves 203 and 2| respectively. The electric circuit forcontrolling the operation of the solenoid valve 94 is the same as in thefirst described embodiment of the invention and includes the foot switch|2|, steering wheel switch means I2, the fuse I l1 and the battery I I4.A switch means 224 carried by a gear shift lever 226 has been added tothe electric circuit for this embodiment. This switch means is equallyapplicable to the electric control circuit illustrated in Figure l. Incertain types of trucks, two transmission mechanisms are used forincreasing the number of available gear ratios, and in such instances,it is sometimes necessary that the operator of the vehicle use bothhands and both feet in shifting gears, the hands being applied to thegear shift 'levers and one foot being applied to the clutch pedal of thevehicle, and the other foot being applied to the gas throttle to controlthe engine speed for shifting gears of both transmissions substantiallysimultaneously. In such case there is no opportunity of using the footswitch |2| and y'accordingly the switch 224 is operatively mounted uponone of the transmission gear shift levers so as to maintain the electriccontrol circuit closed during the shifting operations. This switch meanshere consists of a pair of electric Contact members 221'and 228. whichare engaged and dis-engaged by a bridge contact member 22'9 mounted on aguided stem 23| forming a A spring 232 normally urges the bridge member229 to a disengaged position. 'Ihe handle 23| is preferably positionedadjacent to the top of the gear shift lever 226 and may be engaged bythe hand of the operator in operating the lever to elevate the bridgecontact member 22S to close the electric circuit.

The electric switch means |62 illustrated in the nrst embodiment inconjunction with the foot pedal is preferably also used in the presentembodiment for maintaining the control circuit closed during manualoperation of the brake system.

The master control valves 202 and 2|1 are oi identical construction andare similar in construction to valve mechanism 59 of the iirstembodiment. Each of these master valve mechanisrns includes a valve body233 providing the opposed-ended valve chambers 234 and 236 at oppositesides of an intermediate chamber 231. Valves 23S and 239 are mounted inthe chambers 234 and 23 and are connected by a common valve stem 24| forsimultaneous movement, the arrangement being such that upon elevation ofthe valves, valve 233 moves to a seated position and valve 238 moves toan open position and upon downward movement of the valves, valve 238seats while valve 239 moves to open position. In the case of valve 203,the lower chamber 235 is connected to conduit 202 before-mentionedleading to the foot control valve 20|. The intermediate chamber 231 isconnected by conduit 244 aforementioned to the propelling vehicle brakeunits. The upper chamber 234 is connected by conduit 243 to a flowreducer B2 of the type described in connection with the rst embodimentand thence by conduit 244 to the subatmospheric source |96. In the caseof master valve 2|1, the lower valve chamber is connected to conduit 2|Gleading to the hand valve 2|3 aforementioned, the intermediate chamberis connected by conduit 246 to the brake units of the trailer, and theupper chamber is connected by conduit 241 to the source conduit 244.

Actuation of the master valves 203 and 2|1 is controlled by thepneumatic actuators 222 and 223 in a manner similar to that described inconnection with the iirst embodiment. Each of these actuators include anair chamber 248 having mounted thereacross a iiexible diaphragm 249operatively connected by a plate 25| and a stem 252 to the valve stem24| aforementioned. Normally the valves 238 and 239 are urged to anupward position by means of a coil spring 253 mounted in a chamber abovethe chamber ,d

wardly and valves 238 and 239 move to a seated and unseated positionrespectively.

The operation of the vacuum system will Ibe clear from the foregoing andmay be summarized as follows. In the closed position of the electriccontrol circuit, Solenoid valve mechanism 74 is energized so as to openvalve |0|' and close valve |03 thereof. In such position conduits 2|Sand 22| are communicated so as to evacuate the pneumatic chambers 248 ofthe master valves 203 and 2| 1 to thereby cause a seating of valves 23Bthereof and an opening of valves 238 thereof. In this position of themaster valves, conduits 204 and 2|8 leading to the truck and trailerbrake units are communicated to the atmospheric ports of the foot andhand valves through the master valves. Upon release of the steeringwheel, the solenoid is de-energized and the valves |0|' and |03' movedto reverse positions from those above described, thereby cutting off thesource of reduced pressure and supplying atmospheric air pressure to thepneumatic actuators 222 and 223, which in turn permits an elevating ofthe valve assemblies by springs 253 of the master valves. In such case,sub-atmospheric pressure is communicated to the vehicle brake lines byway of conduit 244, reducer 62', and through the upper and intermediatechambers of master valve 203, and sub-atmospheric air is communicated tothe trailer brake units through conduit 244, conduit 241 and the upperand intermediate chambers of master valve 2|1.

It will be noted in connection with the vacuum operation, that the samesafeguards against accidental opening of the electric circuit andagainst depletion of the air power source as n the case of the iirstembodiment. A partial depletion of the vacuum source will causepneumatic actuators 222 and 223 to operate to communicate the sourcewith the truck units as described in connection with the iirstembodiment. Also it will be noted that the full force and effect of thevacuum source is communicated to the brake lines during automaticoperation rather than a reduced portion thereof as in the case of thepressure system.

In both of the operating circuits illustrated in Figures l and 2, thesolenoid is illustrated in an energized position for clarity ofoperation and accordingly it is to be considered that in these twoviews, the electric switch means ||2 or one of the other electricswitches in the circuit, is closed.

While both of the systems illustrated in Figures l and 2 are adapted foruse with both the truck and trailer units, it will be clear that thesystems may be simplied for sole use with a truck, where a trailer isnot used, by deleting the conduits and valve incorporated in thetrailer' iiuid circuit. In the case oi the pressure system illustratedin Figure l, such deletion would include the hand valve 39, the two-Waycheck valve 43, the retarder device 62 and the connecting conduits. Inthe case of the vacuum operated system illustrated in Figure 2, suchdeletion would include hand valve 2|3, the master valve 2|1, the flowretarder 62 and the connecting conduits.

I claim:

l. In a safety brake control mechanism for automotive vehicles havingiluid pressure operated brake mechanisms and including a nuid powersource and va steering wheel and electric switch means carried by saidwheel and manually operated upon gripping and releasing of the wheel andan electric control valve connected in a fluid circuit between saidsource and said brake mechanisms and in an electric circuit with saidswitch means for providing fluid communication of said source with saidbrake mechanisms upon release of said steering wheel and to disconnectsaid source and brake mecha.- nisms upon gripping of said steeringwheel, a pressure responsive valve means in said uid circuit operativeto communicate said source and brake mechanisms upon a pre-determineddepletion of said source.

2. In a safety brake control mechanism for automotive vehicles havingfluid pressure operated brake mechanisms and including a uid powersource and a steering wheel and electric switch means carried by saidwheel and manually operated upon gripping and releasing of the Wheel,the combination of an electrically controlled valve and a pressureresponsive valve connected in a fluid circuit between said source `andsaid brake mechanisms and connected in an electric circuit with saidswitch means and functioning to disconnect said source and said brakemechanisms upon gripping of said wheel and to communicate said sourcewith said brake mechanisms upon release of said wheel and/or upon apredetermined depletion of said source.

3. In a safety brake control mechanism for automotive vehicles havingfluid pressure operated brake mechanisms and including a fluid powersource and a steering wheel and electric switch means carried by saidsteering wheel and manually operated upon gripping and releasing of thewheel, valve means connected between said source and brake mechanisms,resilient means urging said valve means to open position, pneumaticmeans for closing Said valve means against the action of said resilientmeans, an electrically controlled valve connected between said sourceand said pneumatic means and connected in an electric circuit with saidswitch means and functioning upon gripping of said wheel to communicatesaid source and pneumatic means to close said valve means `andfunctioning upon releasing of said Wheel to disconnect said source andpneumatic means to thereby cause an opening of said valve means underthe action of said resilient means to communicate said source and brakemechanisms.

4. In a safety brake control mechanism lor automotive vehicles havingfluid pressure operated brake mechanisms and including a fluid powersource and a steering wheel, electric switch means carried by saidsteering wheel and manually closed and opened upon respectively grippingand releasing of said wheel, a valve spring pressesd to open positionconnected between said source and said brake mechanisms, a pneumaticactuator connected to said valve for closing same, a solenoid valvespring pressed to closed position connected between said source and saidactuator and connected in an electric circuit with said switch means andconstructed to open upon closing of said circuit.

5. In a safety brake control mechanism for automotive vehicles havingfluid pressure operated brake mechanisms and including a uid powersource and a steering wheel, electric switch means carried by said wheeland manually closed and opened upon respectively gripping and releasingof said wheel, an electrically controlled fluid valve means connected ina fluid circuit between said source and said brake mechanisms andconnected in an electric circuit With said switch means and constructedand operated to disconnect said source and brake mechanisms upongripping of said steering wheel and to communicate said source and brakemechanisms upon release of said steering wheel, said fluid valve meansincluding as part thereof a solenoid operated valve normally springpressed to closed position and displaced to open position uponenergizing of the solenoid therefor, and manually operated means forlocking said last named valve in open position.

6. In a safety brake control mechanism for automotive vehicles havingpneumatic brake mechanisms and a source of air under pressure and asteering wheel, electric switch means carried by said steering wheel andmanually closed and opened respectively upon gripping and releasing orsaid wheel by the operator of the vehicle, a pneumatically operatedvalve normally spring pressed to open position and connected in a fluidcircuit between said source and said brake mechanisms, a pneumaticactuator for said valve connected thereto for displacement of said valveto closed position upon application of air pressure to said actuator, avalve normally spring pressed to closed position connected between saidsource and said pneumatic actuator, a solenoid `actuator connected tosaid last named valve for displacement of the latter to open positionupon energizing of said solenoid actuator, said solenoid actuator beingconnected in an electric circuit with said'switch means and beingrespectively energized and de-energized upon gripping and releasing ofsaid wheel.

7. In a safety brake control mechanism for automotive vehicles havingpneumatically operated brake mechanisms and a sub-atmospheric airpressure source for operating said mechanisms and a steering wheel,electric switch means carried by said steering wheel and manually closedand opened respectively upon gripping and releasing of the wheel by theoperator of the vehicle, a valve normally spring pressed to openposition connected between said source and said mechanisms, a pneumaticactuator connected to said valve and operative upon `application ofsub-atmospheric pressure to said actuator to close said valve, a secondvalve connected between said source and said pneumatic actuator andnormally spring pressed to closed position, and a solenoid actuator forsaid second valve operative upon energizing of said solenoid actuator toopen said second valve and being connected in an electric circuit `withsaid switch means whereby said solenoid actuator is respectivelyenergized and de-energized upon gripping and releasing of said steeringWheel.

RAYMOND E. COX.

